Let's go through first form of the parabola.

                    f ( x ) = a ( x - h )²  + k

There are two pieces of information regarding the parabola which we can instantly get from this function.  First, if a is +ve then the parabola will open up and if a is +ve then the parabola will open down. Second, the vertex of the parabola is the point ( h, k ) .  Be very careful with signs while getting the vertex here.

So, while we are lucky sufficient to have this form of the parabola we are given the vertex for free.